A U.S. appeals court has dismissed a long-running patent infringement lawsuit lodged against Lawson Software by ePlus.

EPlus first sued Lawson, an ERP (enterprise resource planning) company Infor acquired in 2011, in 2009, alleging that a number of configurations of Lawson’s procurement software infringed on patents it held.

In May 2011, ePlus won an injunction against Lawson, which then redesigned its software in order to eliminate any infringement.

EPlus subsequently claimed Lawson had violated the injunction, arguing the redesigned software wasn’t measurably different from the original. The court sided with ePlus, finding Lawson in contempt and fining it US$18 million.

Lawson appealed, and ultimately prevailed in a ruling last week by the U.S. Court of Appeals for the Federal Circuit, which had already thrown out a number of ePlus’s claims.

During Lawson’s appeals process, the U.S. Patent and Trademark Office finished a reexamination of an ePlus patent that contained its remaining claim against Lawson, finding the claim invalid, according to the ruling. The court has vacated its contempt order and the injunction.

When a lower court formally dismisses the ePlus suit, Infor will be free to “sell, market, service and support its procurement software,” the company said in a statement.

“Where other software companies chose to acquiesce to ePlus’s litigation demands and settle meritless claims, Lawson—now Infor—on principle decided to contest ePlus’ patent claims and stand up against the anti-competitive tactics that ePlus employed through the court system,” Infor senior vice president and general counsel Gregory Giangiordano said in a statement.

Giangiordano was apparently alluding to cases such as the patent suit ePlus brought against procurement software vendor Ariba, which is now owned by SAP. In 2005, Ariba settled the case, agreeing to pay ePlus $37 million.

An ePlus spokesman didn’t immediately respond to a request for comment Wednesday.